Coagulation Activation and Organ Dysfunction Following Cardiac Surgery

Cardiovascular Safety of Celecoxib after Cardiac Surgery with Cardiopulmonary Bypass: A Retrospective Cohort Study

BACKGROUND

Cardiac surgery is a highly invasive procedure resulting in hypercoagulability due to thoracotomy and cardiopulmonary bypass (CPB). The long-term use of selective cyclooxygenase-2 inhibitors has been shown to increase the risk of adverse cardiovascular (CV) events such as myocardial infarction. This study aimed to determine whether short-term prescription of celecoxib increases CV events in patients who have undergone cardiac surgery with CPB.

METHODS

This retrospective observational study included 16,141 patients (≥20 years) who had undergone cardiac surgery with CPB between April 1, 2008 and March 31, 2016. Patients who underwent coronary artery bypass grafting were excluded. Patients who received celecoxib (n = 904) and acetaminophen (n = 5,002) from postoperative day 0 to 30 were extracted and matched by propensity score (PS). The primary outcomes were all-cause death and CV events, defined as coronary artery disease, ischemic stroke, pulmonary embolism, and venous thrombosis, coded using International Classification of Diseases-10 within 30 days after the first postoperative prescription of either medication. Results were assessed using Kaplan-Meier survival analysis and multivariate Cox regression analysis.

RESULTS

PS matching created 885 pairs. Multivariate Cox regression analysis showed that prescription of celecoxib after cardiac surgery was not associated with an increase in the primary outcomes when compared with prescription of acetaminophen (hazard ratio, 0.76; 95% confidence interval, 0.35-1.65).

CONCLUSIONS

The prescription of celecoxib in patients who had undergone cardiac surgery with cardiopulmonary bypass was not statistically different from the prescription of acetaminophen in the incidence of CV events and death.

Tranexamic acid after cardiopulmonary bypass does not increase risk of postoperative seizures: a retrospective study

OBJECTIVE

To evaluate the effects of administering tranexamic acid (TXA) after cardiopulmonary bypass, instead of after anesthesia induction, on postoperative seizures and blood transfusion requirements.

METHODS

Adult patients who underwent valve surgery and/or coronary artery bypass grafting at West China Hospital between July 1, 2011 and December 31, 2016 were retrospectively analyzed. Patients either received TXA after bypass (n = 2062) or not (n = 4236). Logistic regression and propensity score matching analysis were performed to assess effects of TXA on postoperative seizures and blood product requirements in hospital.

RESULTS

Among 6298 patients, seizures occurred in 2.4% (102/4236) in the no-TXA group and 2.7% (56/2062) in the TXA group (P = 0.46). The number of patients receiving any blood products was greater in the no-TXA group (57.3%, 2428/4236) than in the TXA group (53.1%, 1095/2062) (P < 0.01), and the volume of blood products was also greater in the no-TXA group (1.5 vs. 1.0 units, P < 0.01). TXA was not associated with increased incidence of postoperative seizures (adjusted OR 1.16, 95% CI 0.83-1.62) but was associated with lower incidence of a requirement for blood products (adjusted OR 0.82, 95% CI 0.73-0.92). Similar results were obtained after patients from the two groups were matched based on propensity scoring. TXA was associated with reduced requirements for fresh frozen plasma, platelets and cryoprecipitate, but not red blood cells.

CONCLUSIONS

Administering TXA after bypass may reduce requirements for blood products without increasing risk of seizures following cardiac surgery.

A Comprehensive Review of Risk Factor, Mechanism, and Management of Left Ventricular Assist Device-Associated Stroke

The use of left ventricular assist devices (LVADs) has been increasing in the last decade, along with the number of patients with advanced heart failure refractory to medical therapy. Ischemic stroke and intracranial hemorrhage remain the leading causes of morbidity and mortality in LVAD patients. Despite the common occurrence and the significant outcome impact, underlying mechanisms and management strategies of stroke in LVAD patients are controversial. In this article, we review our current knowledge on pathophysiology and risk factors of LVAD-associated stroke, outline the diagnostic approach, and discuss treatment strategies.

Increased Risk of Perioperative Ischemic Stroke in Patients Who Undergo Noncardiac Surgery with Preexisting Atrial Septal Defect or Patent Foramen Ovale

OBJECTIVES

To evaluate whether a preoperative diagnosis of atrial septal defect (ASD) or patent foramen ovale (PFO) is associated with perioperative stroke in noncardiac surgery and their outcomes.

DESIGN

Retrospective cohort analysis.

SETTING

United States hospitals.

PARTICIPANTS

Adults patients (≥18 years old) who underwent major noncardiac surgery from 2010 to 2015 were identified using the Healthcare Cost and Utilization Project's National Readmission Database.

INTERVENTIONS

Preoperative diagnosis of ASD or patent foramen ovale.

MEASUREMENTS AND MAIN RESULTS

Among the 19,659,161 hospitalizations for major noncardiac surgery analyzed, 12,248 (0.06%) had a preoperative diagnosis of ASD/PFO. Perioperative ischemic stroke occurred in 723 (5.9%) of patients with ASD/PFO and 373,291 (0.02%) of those without ASD/PFO (adjusted odds ratio [aOR], 16.7; 95% confidence interval [CI]: 13.9-20.0). Amongst the different types of noncardiac surgeries, obstetric, endocrine, and skin and burn surgery were associated with higher risk of stroke in patients with pre-existing ASD/PFO. Moreover, patients with ASD/PFO also had an increased in-hospital mortality (aOR, 4.6, 95% CI: 3.6-6.0), 30-day readmission (aOR, 1.2, 95% CI: 1.04-1.38), and 30-day stroke (aOR, 7.2, 95% CI: 3.1-16.6). After adjusting for atrial fibrillation, ischemic stroke remained significantly high in the ASD/PFO group (aOR: 23.7, 95%CI 19.4-28.9), as well as in-hospital mortality (aOR: 5.6, 95% CI 4.1-7.7), 30-day readmission (aOR: 1.19, 95%CI 1.0-1.4), and 30-day stroke (aOR: 9.3, 95% CI 3.7-23.6).

CONCLUSIONS

Among adult patients undergoing major noncardiac surgery, pre-existing ASD/PFO is associated with increased risk of perioperative ischemic stroke, in-hospital mortality, 30-day stroke, and 30-day readmission after surgery.

Effect of High-Volume Hemofiltration in Critically Ill Patients: A Systematic Review and Meta-Analysis

Background

Studies have been carried out to assess the efficacy of high-volume hemofiltration (HVHF) among critically ill patients. However, it is currently unclear whether HVHF is really valuable in critically ill patients.

Material/Methods

Randomized controlled trials evaluating HVHF for critically ill adult patients were included in this analysis. Three databases were searched up to July 27, 2018. The relative risk (RR), mean difference (MD), and 95% confidence intervals (CI) were determined.

Results

Twenty-one randomized controlled trials were included in this analysis. Overall, HVHF was associated with lower mortality compared with control measures (RR=0.88, 95% CI=0.81 to 0.96, P=0.004) in critically ill patients. Sub-analysis revealed HVHF reduced mortality in sepsis and acute respiratory distress syndrome patients, but no similar effect in other diseases. HVHF decreased levels of plasma tumor necrosis factor and interleukin 6. The heart rate of the HVHF group after treatment was slower than the control group, while we found higher mean arterial pressure in the HVHF group, but oxygenation index was not significantly different between the two groups. HVHF had no remarkable influence on acute physiological and chronic health evaluation score (APACHE II score) compared with the control group.

Conclusions

HVHF might be superior to conventional therapy in critically ill patients.

Early High-Volume Hemofiltration versus Standard Care for Post-Cardiac Surgery Shock. The HEROICS Study

RATIONALE

Post-cardiac surgery shock is associated with high morbidity and mortality. By removing toxins and proinflammatory mediators and correcting metabolic acidosis, high-volume hemofiltration (HVHF) might halt the vicious circle leading to death by improving myocardial performance and reducing vasopressor dependence.

OBJECTIVES

To determine whether early HVHF decreases all-cause mortality 30 days after randomization.

METHODS

This prospective, multicenter randomized controlled trial included patients with severe shock requiring high-dose catecholamines 3-24 hours post-cardiac surgery who were randomized to early HVHF (80 ml/kg/h for 48 h), followed by standard-volume continuous venovenous hemodiafiltration (CVVHDF) until resolution of shock and recovery of renal function, or conservative standard care, with delayed CVVHDF only for persistent, severe acute kidney injury.

MEASUREMENTS AND MAIN RESULTS

On Day 30, 40 of 112 (36%) HVHF and 40 of 112 (36%) control subjects (odds ratio, 1.00; 95% confidence interval, 0.64-1.56; P = 1.00) had died; only 57% of the control subjects had received renal-replacement therapy. Between-group survivors' Day-60, Day-90, intensive care unit, and in-hospital mortality rates, Day-30 ventilator-free days, and renal function recovery were comparable. HVHF patients experienced faster correction of metabolic acidosis and tended to be more rapidly weaned off catecholamines but had more frequent hypophosphatemia, metabolic alkalosis, and thrombocytopenia.

CONCLUSIONS

For patients with post-cardiac surgery shock requiring high-dose catecholamines, the early HVHF onset for 48 hours, followed by standard volume until resolution of shock and recovery of renal function, did not lower Day-30 mortality and did not impact other important patient-centered outcomes compared with a conservative strategy with delayed CVVHDF initiation only for patients with persistent, severe acute kidney injury. Clinical trial registered with www.clinicaltrials.gov (NCT 01077349).

Inflammatory response and extracorporeal circulation

Patients undergoing cardiac surgery with extracorporeal circulation (EC) frequently develop a systemic inflammatory response syndrome. Surgical trauma, ischaemia-reperfusion injury, endotoxaemia and blood contact to nonendothelial circuit compounds promote the activation of coagulation pathways, complement factors and a cellular immune response. This review discusses the multiple pathways leading to endothelial cell activation, neutrophil recruitment and production of reactive oxygen species and nitric oxide. All these factors may induce cellular damage and subsequent organ injury. Multiple organ dysfunction after cardiac surgery with EC is associated with an increased morbidity and mortality. In addition to the pathogenesis of organ dysfunction after EC, this review deals with different therapeutic interventions aiming to alleviate the inflammatory response and consequently multiple organ dysfunction after cardiac surgery.

The preoperative neurological evaluation

Neurological diseases are prevalent in the general population, and the neurohospitalist has an important role to play in the preoperative planning for patients with and at risk for developing neurological disease. The neurohospitalist can provide patients and their families as well as anesthesiologists, surgeons, hospitalists, and other providers guidance in particular to the patient's neurological disease and those he or she is at risk for. Here we present considerations and guidance for the neurohospitalist providing preoperative consultation for the neurological patient with or at risk of disturbances of consciousness, cerebrovascular and carotid disease, epilepsy, neuromuscular disease, and Parkinson disease.

Perioperative stroke

It is increasingly recognized that one can identify a higher risk patient for perioperative stroke. The risk of stroke around the time of operative procedures is fairly substantial and it is recognized that patients initially at risk for vascular events are those most likely to have this risk heightened by invasive procedures. Higher risk patients include those of advanced age and there is a cumulative risk, over time, of coexistent hypertension, atherosclerosis, diabetes mellitus, cardiac disease and clotting disorders. There are a number of possible mechanisms associated with the procedure (e.g., preoperative hypercoagulability, holding of antithrombic therapy at the time of the procedure and cardiac arrhythmia) that can promote a thrombo-embolic event. Examples of these include: direct mechanical trauma to extracranial vessels related to operations on the head and neck; and vascular injury as a consequence of vascular and innovative endovascular procedures affecting the cerebral circulation (e.g., carotid endarterectomy, extracranial or intracranial angioplasty with stenting, and use of the MERCI clot retrieval device), as well as various endovascular methods that have been developed to obliterate cerebral aneurysms and arteriovenous malformations as an alternative to surgical clipping and surgical resection, respectively.

Effect of cardiopulmonary bypass on thrombin generation and protein C pathway

OBJECTIVE

The purpose of this study was to evaluate the mechanisms of cardiopulmonary bypass (CPB)-induced dysregulation between thrombin and its regulatory anticoagulant activated protein C (APC).

DESIGN

A prospective observational cohort study.

SETTING

A tertiary care university hospital and associated research laboratory.

PATIENTS

Twenty patients undergoing elective coronary artery bypass surgery with (n = 10) or without CPB (n = 10).

INTERVENTIONS

Blood samples were collected at 7 time points: preinduction; after heparin; 1 hour after the institution of CPB (or the completion of distal anastomoses in off-CPB group); after protamine; and at 0, 4, and 18 hours in the Intensive care unit (ICU). Samples were analyzed for prothrombin fragments (F1+2), thrombin-antithrombin complexes, protein C (PC), APC, soluble thrombomodulin (sTM), and soluble endothelial protein C receptor (sEPCR).

MEASUREMENTS AND MAIN RESULTS

F1+2 levels increased significantly 1 hour after the initiation of CPB in comparison with baseline (2.7 ± 0.5 v 0.5 ± 0.2 nmol/L, p < 0.001) (mean ± standard deviation) and remained elevated until 4 hours after ICU admission (p < 0.001). In contrast, APC levels did not show any significant changes over time in either group. sEPCR, sTM, and PC levels did not change during CPB although sEPCR decreased significantly after the termination of CPB compared with baseline in the CPB group.

CONCLUSIONS

Exposure to CPB is associated with a distinct thrombin surge that continues postoperatively for 4 hours. The impaired ability to generate APC reflects a complex process that is not associated with increased levels of sEPCR and thrombomodulin during CPB. Further studies are required to evaluate the regulation of the host APC response in cardiac surgery.

Increased preoperative thrombin generation and low protein S level associated with unfavorable postoperative hemodynamics after coronary artery bypass grafting

In a previous study, preoperative levels of activated protein C (APC) were associated with unfavorable postoperative hemodynamics after coronary artery bypass grafting (CABG). Protein C is activated by thrombin. Protein S, the cofactor of activated protein C, has activated protein C-independent anticoagulant activity and cytoprotective effects. Therefore, the objective of this study was to test whether preoperative, baseline levels of either thrombin or protein S were associated with hemodynamic performance or markers of myocardial damage after CABG. One hundred patients undergoing elective on-pump CABG were prospectively studied. Prothrombin fragment F1+2 (a marker of thrombin generation) and free protein S were measured preoperatively and cardiac index, systemic vascular resistance index (SVRI), and pulmonary vascular resistance index (PVRI) were measured serially thereafter at fixed time points. Cardiac biomarkers CK-MBm and TnT were measured postoperatively. There was an inverse correlation between preoperative F1+2 and free protein S levels (r= —0.30, p=0.003). High preoperative F1+2 and low preoperative protein S levels were associated with a less favorable hemodynamic profile postoperatively. Patients with F1+2 in the highest decile (≥0.85 nmol/l) and patients with preoperative protein S in the lowest decile (≤63%) had lower CI values, and higher pulmonary and systemic vascular resistance index values postoperatively than comparison patients. Preoperative F1+2 or protein S did not correlate with postoperative cardiac biomarker levels. Baseline activation of coagulation and the balance between pro-coagulant and anti-coagulant factors preoperatively might have implications for postoperative hemodynamic recovery after CABG.

Risk of stroke after surgery in patients with and without chronic atrial fibrillation

SUMMARY BACKGROUND

The extent to which chronic atrial fibrillation affects the risk of postoperative stroke is largely unknown.

OBJECTIVES

We sought to determine the 30-day rate of stroke among patients with and without chronic AF who underwent 10 different types of surgery.

PATIENTS/METHODS

The crude incidence of stroke was retrospectively determined using a population-based linked administrative database of hospitalized patients who underwent specified operations between 1 January 1996 and 30 November 2005. The risk of stroke in patients with AF was adjusted for age, race, sex, presence of diabetes, heart failure, hypertension and prior stroke.

RESULTS

The overall 30-day rate of stroke in 69 202 patients with chronic AF was 1.8% (95% CI, 1.7-1.9%) vs. 0.6% (CI, 0.58-0.62%) in 2 470 649 patients without AF. The risk-adjusted odds of a postoperative stroke in patients with chronic AF were 2.1 (CI, 2.0-2.3). The highest incremental difference in the crude rate of stroke was observed in patients undergoing neurologic or vascular surgery, with a difference of approximately 2%.

CONCLUSION

Patients with chronic AF had twice the risk of postoperative stroke. Randomized trials are needed to determine if aggressive perioperative anticoagulation can reduce the incidence of postoperative stroke in patients with AF.

Intima-media thickness of common carotid and brachial arteries and prothrombin fragment 1 + 2 are associated with left ventricular diastolic dysfunction in patients with myocardial infarction

AIMS

To investigate the association between intima-media thickness of brachial and common carotid arteries and factors of the coagulation- and fibrinolysis-system with left ventricular diastolic dysfunction in patients with a previous myocardial infarction.

PATIENTS AND METHODS

One hundred and twenty three patients, men (76%) and women (24%) aged between 32 and 81 years with a history of previous acute myocardial infarction were included. B-mode ultrasound of common carotid and brachial arteries and echocardiography with tissue Doppler imaging (TDI) were evaluated. Factors of the coagulation- and fibrinolysis-system were also measured.

RESULTS

In patients with previous myocardial infarction, late diastolic filling time was significantly and positively associated with log Prothrombin fragment 1 + 2 (P < 0.001) and with calculated intima-media area (cIMa) of the both common carotid and brachial arteries (P < 0.05). Mitral early-to-late flow velocity ratio (E/A) was significantly and negatively associated with log Prothrombin fragment 1 + 2 (P < 0.001), total cholesterol and cIMa of the both common carotid and brachial arteries (P < 0.05). Moreover both late diastolic filling time and mitral E/A correlated significantly with age and systolic blood pressure. In stepwise multiple regression analysis, log Prothrombin fragment 1 + 2 remained the only variable with independent significant correlation to late diastolic filling time and mitral E/A.

CONCLUSIONS

In a population sample of patients with myocardial infarction, late diastolic filling time and mitral E/A were associated with cIMa of common carotid and brachial arteries, systolic blood pressure, and prothrombin fragment 1 + 2, suggesting a relationship between diastolic dysfunction, thrombin generation and atherosclerosis.

[Microcirculatory alterations in critically ill patients: pathophysiology, monitoring and treatments]

Microcirculation represents a complex system devoted to provide optimal tissue substrates and oxygen. Therefore, pathophysiological and technological knowledge developments tailored for capillary circulation analysis should generate major advances for critically ill patients' management. In the future, microcirculatory monitoring in several critical care situations will allow recognition of macro-microcirculatory decoupling, and, hopefully, it will promote the use of treatments aimed at preserving tissue oxygenation and substrate delivery.

Predictors of ischemic stroke after hip operation: a population-based study

BACKGROUND

Hip operation (total hip arthroplasty [THA] or fracture repair) is the most common noncardiac surgical procedure performed in patients age 65 years and older.

OBJECTIVE

To determine the predictors of ischemic stroke in patients who have undergone hip operation.

DESIGN

Population-based historical cohort study, in which postoperative ischemic strokes were identified from medical record review for stroke diagnostic codes and brain imaging results and were confirmed by physician review.

SETTING

Tertiary care center in Olmsted County, Minnesota.

PATIENTS

Residents of Olmsted County who underwent hip surgical procedure.

MEASUREMENTS

Incidence of ischemic stroke within 1 year of hip operation.

RESULTS

In total, 1606 patients underwent 1886 hip procedures from 1988 through 2002 and were observed for ischemic stroke for 1 year after their procedure. Sixty-seven ischemic strokes were identified. The rate of stroke at 1 year after hip operation was 3.9%. In univariate analysis, history of atrial fibrillation (hazard ratio [HR], 2.16; P = 0.005), hip fracture repair vs. total hip arthroplasty (HR, 3.80; P < 0.001), age 75 years or older (HR, 2.20; P = 0.02), aspirin use (HR, 1.8; P = 0.01), and history of previous stroke (HR, 4.18; P < 0.001) were significantly associated with increased risk of stroke. In multivariable analysis, history of stroke (HR, 3.27; P < 0.001) and hip fracture repair (HR, 2.74; P = 0.004) were strong predictors of postoperative stroke.

CONCLUSIONS

This population-based historical cohort of patients with hip operation had a 3.9% cumulative probability of ischemic stroke over the first postoperative year. Hip fracture repair and history of stroke were the strongest predictors of this complication.

Perioperative management of aspirin resistance after off-pump coronary artery bypass grafting: possible role for aprotinin

BACKGROUND

Aspirin is the only drug proven to reduce saphenous vein graft (SVG) failure, but aspirin resistance (ASA-R) frequently occurs after off-pump coronary artery bypass grafting (OPCAB). The factors, mechanism, and best means for preventing and/or treating ASA-R have not been established. This study hypothesizes that thrombin production during OPCAB stimulates this acquired ASA-R.

STUDY DESIGN AND METHODS

A nonrandomized prospective cohort of 255 patients (n=465 SVG) who underwent OPCAB with varied use of aprotinin (21%) and different SVG preparation techniques (standard, 56% vs. low-pressure, 44%) was analyzed. A surplus SVG segment was obtained to assess endothelial integrity. ASA-R was determined at baseline, after surgery, and on Days 1 and 3 by three assays. The effects of aprotinin on thrombin responsiveness were analyzed by means of whole-blood aggregometry, SVG tissue factor (TF) activity, and transcardiac thrombin production (i.e., F1.2 levels in aorta versus coronary sinus). SVG patency was assessed on Day 5 with multichannel CT angiography.

RESULTS

ASA-R developed in 42 percent of patients after OPCAB. Multivariate analysis showed that ASA-R, endothelial integrity, and target size independently predicted early SVG failure. Aprotinin use was associated with: 1) reduced postoperative ASA-R (15%); 2) decreased platelet (PLT) response to thrombin; 3) reduced TF activity within SVG segments; 4) decreased transcardiac thrombin gradient; and 5) improved SVG patency.

CONCLUSION

ASA-R is a common post-OPCAB event whose frequency may be reduced by intraoperative use of aprotinin, possibly via TF and thrombin suppression. Improved perioperative PLT function after OPCAB may also inadvertently enhance the clinical relevance of these potential antithrombotic effects.

The minimized extracorporeal circulation system causes less inflammation and organ damage

The minimized extracorporeal circulation system (MECC) is being used to reduce priming volume and blood/polymer contact during cardiac procedures. In this study, we evaluated the efficacy and potential advantages of the system in coronary artery bypass graft (CABG) patients. We included two groups of patients destined for CABG in a prospective, randomized study: Group A was operated on the usual pump (n = 30) while Group B was operated using the MECC (n = 50). Pre-operative demographics, intra-operative times and values as well as a series of post-operative outcome data (blood loss, transfusion requirements, ventilation time, ICU and hospital stay) were recorded. CK, CK-MB, troponin-T, IL-6 and IL-8 were measured. Pre-operative and post-operative lung function were assessed. In the MECC-operated group, patients developed less post-operative troponin-T (0.2 ± 0.3 vs. 0.5 ± 0.5 ng/mL, p=0.031) and less IL-8 (13.8 ± 5 vs. 22.5 ± 0.5 µg/L, p = 0.05). While blood loss was comparable in both groups, packed red blood cells and fresh frozen plasma were given less frequently in the MECC group (p = 0.015 resp. 0.022). The one-tailed Student’s t-test revealed shorter bypass time in the MECC group (74 ± 17 vs. 82 ± 24 min). There was no difference in ventilation and ICU-time (patients were not treated in a fast-track fashion). The FEV1 was better in the MECC group (relative values: 70.1 ± 18.2% vs. 61.1 ± 12.3%, p = 0.02). Utilization of the MECC may cause less cytokine (IL-8) liberation, owing to less blood/tubing contact, as well as less red blood cell and fresh frozen plasma demand. It may also be the circuit in patients with chronic obstructive pulmonary disease (COPD).

Does the Type of Surgery Effect Systemic Response Following Cardiopulmonary Bypass?

BACKGROUND

Clinical studies conducted to elucidate the systemic response to cardiopulmonary bypass (CPB) did not differentiate possible effect of different types of cardiac surgical pathologies and operations on outcomes and have typically combined different procedures. We hypothesized that valve surgery induces more prominent systemic reaction compared to isolated on-pump CABG.

METHODS

Twenty-seven patients undergoing primary on-pump CABG (Group 1, n = 14) or valve surgery with or without CABG (Group 2, n = 13) were prospectively enrolled. Heparin-bonded circuits were used in all patients. Cardiotomy suction was only used in Group 2. Clinical and laboratory markers were evaluated.

RESULTS

Clinical measurements, including chest tube output, blood transfusion requirement, inotropic support requirement, and duration of ICU stay were not significantly different. Thrombin generation (PF-1.2) was significantly higher in Group 2 (p = 0.001). tPA was also significantly higher in Group 2 at 15 and 60 minutes on CPB (p < 0.01). Group 2 had significantly higher inflammatory response shown by elevation of IL6 (p = 0.005). Neuronal injury markers, S100beta and NSE, were significantly higher at the termination of CPB in Group 2 (p < 0.01). At no point of time course for any marker, Group 1 had significantly higher response compared to Group 2.

CONCLUSIONS

Valve surgery induced more prominent systemic response than CABG. The possible explanations include the difference in baseline disease pathophysiology, and/or difference associated with the procedures such as open systems and use of cardiotomy suction. Future clinical studies assessing systemic response to CPB and therapies to blunt these need consider and account for these observed differences.

Coagulopathy after cardiac surgery may be influenced by a functional plasminogen activator inhibitor polymorphism

BACKGROUND

Cytokine-mediated inflammation and coagulopathy may occur after cardiac surgery. In this study we investigated the temporal pattern of plasminogen activator inhibitor-1 (PAI-1) gene expression after cardiac surgery and its relation with PAI genotype, and obtained preliminary data regarding its relation to perioperative morbidity.

METHODS

The relative change in PAI-1 mRNA 1, 6, and 24 h after cardiopulmonary bypass (CPB) was measured from mononuclear cells in 82 patients undergoing elective cardiac surgery. DNA was analyzed for carriage of the 4G/5G PAI-1 polymorphism.

RESULTS

PAI-1 gene expression decreased after CPB in all patients. A larger reduction in PAI-1 gene expression was observed in homozygous carriers of the 5G allele. Homozygous carriers of the 5G allele were also more likely to receive transfusion of coagulation blood products. There was no relation between change in PAI-1 gene expression and duration of CPB.

CONCLUSIONS

PAI-1 gene expression decreased over time after CPB. We found a link between PAI-1 genotype, PAI gene expression, and transfusion of coagulation products after cardiac surgery.

Anti-inflammatory Strategies and Hemostatic Agents: Old Drugs, New Ideas

Hemostatic abnormalities occur following injury associated with both cardiac and noncardiac surgery. These changes are part of inflammatory pathways with signaling mechanisms that link these diverse pathways. The inflammatory response to surgery is exacerbated by allogeneic blood transfusion by enhancing intrinsic inflammatory activity and directly increasing plasma levels of inflammatory mediators. Surgical patients can be preventively treated with pharmacologic agents to modulate inflammatory responses. Multiple studies have reported preventive pharmacologic therapies to reduce bleeding and the need for allogeneic transfusions in surgery. Strategies for cardiac surgical patients during cardiopulmonary bypass include administration of either lysine analogs, such as epsilon aminocaproic acid and tranexamic acid, or the serine protease inhibitor aprotinin.

Disposition of tissue factor pathway inhibitor during cardiopulmonary bypass

BACKGROUND

The tissue factor (TF) factor (F) VIIa complex activates coagulation FIX and FX to initiate coagulation, and also cleaves protease activated receptors (PARs) to initiate inflammatory processes in vascular cells. Tissue factor pathway inhibitor (TFPI) is the only specific inhibitor of the TF-FVIIa complex, regulating both its procoagulant and pro-inflammatory properties. Upon heparin infusion during cardiopulmonary bypass (CPB), a heparin releasable pool of endothelial associated TFPI circulates in plasma. Following protamine neutralization of heparin, the plasma TFPI level decreases, but does not return completely to baseline, suggesting that during CPB a fraction of the plasma TFPI becomes heparin-independent. We have investigated the structural and functional properties of plasma TFPI during CPB to further characterize how TFPI is altered during this procedure.

METHODS

We enrolled 17 patients undergoing first-time cardiac surgery involving CPB. Plasma samples were obtained at baseline, 5 min and 1 h after start of CPB (receiving heparin), 10 min after protamine administration (off CPB) and 24 h following surgery. Samples were analyzed for full-length and free (non-lipoprotein bound) TFPI antigen by enzyme-linked immunosorbent assay (ELISA) and for TFPI anticoagulant activity using an amidolytic assay. Western blot analysis was used to identify TFPI species of varying molecular weights in three additional patients. Dunnett's test for post hoc comparisons was used for statistical analysis.

RESULTS

The ELISA and Western blot data indicated that an increase in full-length TFPI accounted for most of the heparin releasable TFPI. Following heparin neutralization with protamine, the full-length TFPI antigen returned to baseline levels while the free TFPI antigen and the total plasma TFPI activity remained elevated. This was associated with the appearance of a new 38 kDa form of plasma TFPI identified by Western blot analysis. The 38 kDa form of TFPI did not react with an antibody directed against the C-terminal region of TFPI indicating it has undergone proteolysis within this region. All TFPI measurements returned to baseline 24 h following CPB.

CONCLUSIONS

During CPB the full-length form of TFPI is the predominant form in plasma because of its prompt release from the endothelial surface following heparin administration. Upon heparin neutralization with protamine, full-length TFPI redistributes back to the endothelial surface. However, a new 38 kDa TFPI fragment is generated during CPB and remains circulating in plasma, indicating that TFPI undergoes proteolytic degradation during CPB. This degradation may result in a decrease in endothelium-associated TFPI immediately post-CPB, and may contribute to the procoagulant and proinflammatory state that often complicates CPB.